U.S. patent application number 14/939723 was filed with the patent office on 2017-05-18 for monitoring diversion degradation in a well.
The applicant listed for this patent is SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Andrey Bogdan, Bruno Lecerf.
Application Number | 20170138169 14/939723 |
Document ID | / |
Family ID | 58690886 |
Filed Date | 2017-05-18 |
United States Patent
Application |
20170138169 |
Kind Code |
A1 |
Bogdan; Andrey ; et
al. |
May 18, 2017 |
MONITORING DIVERSION DEGRADATION IN A WELL
Abstract
A degradable diverter is placed in a flow path to divert fluid
flow and exposed to degradation conditions, and after sensing a
response to a pressure wave to determine the diverter has degraded,
placing the well in service. Also, a treatment sequence is
initiated according to a treatment schedule, a degradable diverter
is placed in a flow path to divert treatment fluid, and, before
completing the treatment, an interruption of the treatment schedule
is followed by sensing a response to a pressure wave generated in
the well to determine the status of the degradable diverter. Also,
in a series of stages a degradable diverter is placed in a flow
path, a response to a pressure wave is sensed to confirm placement,
fluid flow is diverted, and the sequence repeated for subsequent
stages.
Inventors: |
Bogdan; Andrey; (Sugar Land,
TX) ; Lecerf; Bruno; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCHLUMBERGER TECHNOLOGY CORPORATION |
Sugar Land |
TX |
US |
|
|
Family ID: |
58690886 |
Appl. No.: |
14/939723 |
Filed: |
November 12, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01V 1/46 20130101; E21B
33/12 20130101; E21B 47/00 20130101; E21B 33/134 20130101; E21B
33/138 20130101; E21B 47/18 20130101; E21B 47/06 20130101; E21B
43/25 20130101; E21B 43/26 20130101 |
International
Class: |
E21B 47/00 20060101
E21B047/00; E21B 47/18 20060101 E21B047/18; E21B 33/12 20060101
E21B033/12 |
Claims
1. A method for treating a well, comprising: (a) placing a
degradable diverter in a flow path of the well to divert treatment
fluid flow from the flow path; (b) exposing the degradable diverter
to degradation conditions; (c) sensing a response to a pressure
wave generated in the well to determine whether the degradable
diverter has substantially degraded; and (d) after determining that
the degradable diverter has substantially degraded, performing an
operation and flowing fluid through the flow path.
2. The method of claim 1, wherein the degradable diverter comprises
a mechanical diverter.
3. The method of claim 1, wherein the degradable diverter comprises
a chemical diversion material.
4. The method of claim 1, wherein the flow path comprises a
perforation or fracture in communication with the well.
5. The method of claim 1, wherein the flow path comprises a first
portion of the wellbore isolated from a second portion of the
wellbore by the diverter.
6. The method of claim 1, further comprising continuously or
periodically generating the pressure wave and sensing the response
to monitor the placement of the diverter, degradation of the
diverter, or a combination thereof.
7. The method of claim 6, wherein the placement or degradation of
the diverter or both are monitored by changes in the sensed
response.
8. The method of claim 6, wherein the pressure wave is generated at
a frequency from 1 per second to 1 per minute.
9. The method of claim 6, wherein the pressure wave generation
comprises a sweep circuit comprising a regularly changing
frequency.
10. The method of claim 9, wherein the pressure wave has
overlapping intervals, and further comprising deconvoluting the
sensed response.
11. The method of claim 6, further comprising automatically sending
data derived from the sensed response to a remote receiver.
12. The method of claim 1, wherein the pressure wave is generated
by a fluid hammer.
13. The method of claim 1, wherein the pressure wave is generated
by a pressure signal emitter device in communication with the
well.
14. The method of claim 1, wherein the flowing of the fluid in (d)
comprises producing reservoir fluid.
15. The method of claim 1, wherein the flowing of the fluid in (d)
comprises fluid injection into a subterranean formation.
16. A method for treating a well, comprising: (a) initiating a
treatment sequence according to a planned treatment schedule
comprising introducing treatment fluid into the well in a plurality
of stages; (b) placing a degradable diverter in a flow path of the
well to divert treatment fluid from the flow path; (c) interrupting
the treatment schedule comprising shutting in the well; (d) sensing
a response to a pressure wave generated in the well to determine
whether the degradable diverter has degraded; and (e) after
determining that the degradable diverter has not degraded,
performing an operation or resuming the treatment sequence.
17. The method of claim 16, wherein the resumption of the treatment
sequence is according to the planned treatment schedule.
18. The method of claim 16, wherein the resumption of the treatment
sequence is according to a new treatment schedule revised in
response to the interruption.
19. The method of claim 16, further comprising exposing the
diverter to degradation conditions; sensing a response to a
pressure wave generated in the well to determine whether the
degradable diverter has degraded; and after determining that the
degradable diverter has degraded, flowing fluid through the flow
path.
20. A method for treating a well, comprising: (a) placing a
degradable diverter in a flow path of the well; (b) sensing a
response to a pressure wave generated in the well to confirm the
placement of the degradable diverter; (c) diverting fluid flow from
the flow path; (d) exposing the diverter to degradation conditions;
(e) sensing a response to a pressure wave generated in the well to
determine whether the degradable diverter has degraded; and (f)
after determining that the degradable diverter has degraded,
performing an operation and flowing fluid through the flow
path.
21. A method for treating a well, comprising: (a) placing a
degradable diverter in a flow path of the well; (b) sensing a
response to a pressure wave generated in the well to confirm the
placement of the degradable diverter; (c) diverting fluid flow from
the flow path; (d) repeating (a)-(c) one or more times for a
plurality of respective degradable diverters placed in respective
flow paths; (e) exposing the diverters to degradation conditions;
(f) sensing a response to a pressure wave generated in the well to
determine whether the degradable diverters have degraded; and (g)
after determining that the degradable diverters have degraded,
placing the well in service and flowing fluid through the flow
paths.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] None.
BACKGROUND
[0002] Existing methods to detect failure of zone isolation or
diverter material include post-treatment pressure analysis or
chemical traces recording. Other methods use distributed pressure
or vibration sensors, such as an optic wire, pre-installed into
casing or coiled tubing. The analysis of reflected pressure waves
has been used to detect fractures or bottom irregularities, and
also to determine or confirm the proper placement of diverters in
fractures or bridge plugs in the wellbore. There are patents
describing ways to analyze pressure wave reflections, such as US
2011/0267922, US 2012/0018150 and U.S. Pat. No. 7,819,188.
[0003] The industry has an ongoing requirements for the development
or improvement of well treatment methods involving the installation
and/or removal of temporary diverters prior to production or
otherwise placing the well in service.
SUMMARY OF DISCLOSURE
[0004] In one aspect, embodiments of the present disclosure relate
to monitoring the degradation of a degradable diverter used to plug
a fluid flow path, within the wellbore or connected to the
wellbore, using the reflection of tube waves, which are also
referred to herein as pressure waves. In some embodiments, the
degradation of the diverter is confirmed before placing the well in
service, e.g., to produce reservoir fluids through the flow path
plugged by the diverter. In some embodiments, the functionality of
the diverter for diversion is confirmed, e.g., following
interruption of a treatment schedule involving shut in of the
well.
[0005] In some embodiments, a method for treating a well comprises:
(a) placing a degradable diverter in a flow path of the well to
divert fluid flow from the flow path; (b) exposing the degradable
diverter to degradation conditions; (c) sensing a response to a
pressure wave generated in the well to determine whether the
degradable diverter has substantially degraded; and (d) after
determining that the degradable diverter has substantially
degraded, placing the well in service and flowing fluid through the
flow path.
[0006] In some embodiments, a method for treating a well comprises:
(a) initiating a treatment sequence according to a planned
treatment schedule comprising introducing treatment fluid into the
well in a plurality of stages; (b) placing a degradable diverter in
a flow path of the well to divert treatment fluid from the flow
path; (c) interrupting the treatment schedule comprising shutting
in the well; (d) sensing a response to a pressure wave generated in
the well to determine whether the degradable diverter has degraded;
and (e) after determining that the degradable diverter has not
degraded, resuming the treatment sequence.
[0007] In some embodiments, a method for treating a well comprises:
(a) placing a degradable diverter in a flow path of the well to
divert treatment fluid from the flow path; (b) sensing a response
to a pressure wave generated in the well to confirm the placement
of the degradable diverter; (c) diverting fluid flow from the flow
path; (d) repeating (a)-(c) one or more times for a plurality of
respective degradable diverters placed in respective flow paths;
(e) exposing the diverters to degradation conditions; (f) sensing a
response to a pressure wave generated in the well to determine
whether the degradable diverters have degraded; and after
determining that the degradable diverters have degraded, placing
the well in service and flowing fluid through the flow paths.
[0008] Other aspects and advantages of the disclosure will be
apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a pressure wave trace diagram for a series of
tests in a simulated borehole, according to embodiments of the
disclosure.
[0010] FIG. 2 is a schematic diagram of a borehole being tested for
the degradation of diverter balls, in accordance with embodiments
of the present disclosure.
[0011] FIG. 3 is a schematic diagram of a borehole being tested for
the degradation of diversion materials in hydraulic passages
connected to the well, such as perforations or fractures, in
accordance with embodiments of the present disclosure.
[0012] FIG. 4 is a process flow diagram for treatment of a well
involving monitoring of diverter degradation in accordance with
some embodiments of the disclosure. [per claims 1-15]
[0013] FIG. 5 is a process flow diagram for treatment of a well
involving checking diverter degradation after interruption of a
treatment schedule in accordance with some embodiments of the
disclosure. [per claims 16-19]
[0014] FIG. 6 is a process flow diagram for treatment of a well
involving monitoring of diverter placement and degradation in
accordance with some embodiments of the disclosure. [per claims
20-21]
DEFINITIONS
[0015] "Above", "upper", "heel" and like terms in reference to a
well, wellbore, tool, formation, refer to the relative direction or
location near or going toward or on the surface side of the device,
item, flow or other reference point, whereas "below", "lower",
"toe" and like terms, refer to the relative direction or location
near or going toward or on the bottom hole side of the device,
item, flow or other reference point, regardless of the actual
physical orientation of the well or wellbore, e.g., in vertical,
horizontal, downwardly and/or upwardly sloped sections thereof.
[0016] Borehole or wellbore--the portion of the well extending from
the Earth's surface formed by or as if by drilling, i.e., the
wellbore itself, including the cased and openhole or uncased
portions of the well.
[0017] Break in--sudden loss of wellhead pressure or rapid increase
in treatment fluid flow rate, e.g. when a fracture is initiated in
a formation.
[0018] Casing/casing string--Large-diameter pipe lowered into an
open hole and cemented in place.
[0019] Closed end--an end of a tube at which there is little or no
compliance, e.g., a capped pipe, and producing a positive
reflection to a positive pressure wave.
[0020] Cluster--a collection of data points with similar
characteristics.
[0021] Confirm--to make sure or demonstrate that something is true,
accurate, or justified; verify; substantiate.
[0022] Deconvoluting--algorithmic processing to reverse the effects
of convolution on recorded data.
[0023] Degradable--a material capable of breaking down, or
chemically deteriorating, or changing state as by dissolution,
sublimation or melting.
[0024] Degradation conditions--conditions at which the process of
degrading a degradable material can initiate or continue.
[0025] As used herein, a degradable diverter placed in a flow
passage has "substantially degraded" when the process of degrading
has progressed to the point where fluid can readily pass through
the flow path.
[0026] Depth--includes horizontal/lateral
distance/displacement.
[0027] Derived (data)--obtained from a specified source. For the
avoidance of doubt, data derived from a specified source may
comprise or consist of the original data per se.
[0028] Determine--to establish or ascertain definitely, as after
consideration, investigation, or calculation.
[0029] Diversion--the act of causing something to turn or flow in a
different direction.
[0030] Diversion material--a substance or agent used to achieve
diversion during stimulation or similar injection treatment; a
chemical diverter.
[0031] Diversion pill--a relatively small quantity of a special
treatment fluid blend used to direct or divert the flow of a
treatment fluid.
[0032] Divert--to cause something to turn or flow in a different
direction.
[0033] Diverter--anything used in a well to cause something to turn
or flow in a different direction, e.g., a diversion material or
mechanical device; a solid or fluid that may plug or fill, either
partially or fully, a portion of a subterranean formation.
[0034] Flow path--a passageway, conduit, porous material or the
like through which fluid may pass.
[0035] Fluid communication--connection via a flow path.
[0036] Fluid hammer--a pressure surge or wave caused when a fluid
in motion is suddenly forced to stop or change direction.
[0037] Formation--a body of rock that is sufficiently distinctive
and continuous that it can be mapped, or more generally, the rock
around a borehole.
[0038] Fracture--a crack or surface of breakage within rock.
[0039] Hydraulic fracturing or "fracturing"--a stimulation
treatment involving pumping a treatment fluid at high pressure into
a well to cause a fracture to open.
[0040] Initiate--to cause a process or action to begin.
[0041] Injection--pumping fluid through the wellbore into the
reservoir for storage or to maintain pressure and/or in a flooding
operation.
[0042] Instantaneous shut-in pressure or ISIP--the shut-in pressure
immediately following the cessation of the pumping of a fluid into
a well.
[0043] Interval--a space between two points or times, e.g., the
space between two points in a well.
[0044] Lateral--a branch of a well radiating from the main
borehole.
[0045] Liner--A casing string that does not extend to the top of
the wellbore, but instead is anchored or suspended from inside the
bottom of the previous casing string.
[0046] Measure--to ascertain the value, number, quantity, extent,
size, amount, degree, or other property of something by using an
instrument or device.
[0047] Minibreak--a brief, unscheduled interruption of a well
treatment lasting less than 24 hours such as for example
interruption stop for refueling the pumps, stop because of
accidents, thunderstorm, insufficient supply of proppant/water.
[0048] Modify--to make partial or minor changes to (something),
typically so as to improve it or to make it less extreme.
[0049] Monitor--to observe, record or detect the progress or
quality of something over a period of time; keep under systematic
review for purposes of control or surveillance.
[0050] Open end--an end of a tube at which there is a large
compliance, e.g., a large (relative to the tube) tank or a lateral
flow passage connection such as at a perforation or fracture open
to the wellbore, and producing a negative reflection to a positive
pressure wave.
[0051] Overlapping--partly coinciding in time or spatial
dimension(s).
[0052] Perforation--the communication tunnel created from the
casing or liner into the reservoir formation, through which fluids
may flow, e.g., for stimulation and/or oil or gas production.
[0053] Perforation cluster--a group of nearby perforations having
similar characteristics.
[0054] Pill--any relatively small quantity of a special blend of
drilling or treatment fluid to accomplish a specific task that the
regular drilling or treatment fluid cannot perform.
[0055] Pressure wave--a periodic pressure disturbance in which
alternating compression and rarefaction are propagated through or
on the surface of a medium without translation of the material;
also known as a tube wave or Stoneley wave.
[0056] Pressure signal emitter--a non-pumping device specially
adapted to form a pressure wave in a wellbore, usually in
communication with the high pressure side (outlet or discharge) of
a fluid pump.
[0057] Progression--a movement or development toward a destination
or a more advanced state, especially gradually or in stages; a
succession; a series.
[0058] Proppant--particles mixed with treatment fluid to hold
fractures open after a hydraulic fracturing treatment.
[0059] Proppant pumping schedule--a pumping sequence comprising the
volume, rate, and composition and concentration of a proppant-laden
fluid, and any associated treatment fluids such as an optional pad,
optional spacers, and an optional flush.
[0060] Receiver--an electrical or computer apparatus that converts
a signal to a file, sound, or visual display.
[0061] Refracturing or refrac--fracturing a portion of a previously
fractured well after an initial period of production. The fractures
from the earlier treatment are called "pre-existing fractures".
[0062] Regularly changing frequency--a frequency (cycles per time)
that varies in an ordered pattern.
[0063] Remote--distant or far away.
[0064] Reservoir--a subsurface body of rock having sufficient
porosity and permeability to store and transmit fluids.
[0065] Re-stimulation--stimulation treatment of any portion of a
well, including any lateral, which has previously been
stimulated.
[0066] Revise--alter in light of developments.
[0067] Sending--cause (a message or computer file) to be
transmitted electronically.
[0068] Shut in--closing a wellbore at the surface, e.g., at or near
the Christmas tree, blowout preventer stack
[0069] Shut-in pressure or SIP--the surface force per unit area
exerted at the top of a wellbore when it is closed, e.g., at the
Christmas tree or BOP stack.
[0070] Simulate--to create a representation or model of something,
e.g., a physical system or particular situation.
[0071] Stage--a pumping sequence comprising a proppant pumping
schedule and a diversion pill pumping schedule, including pads,
spacers, flushes and associated treatment fluids.
[0072] Stimulation--treatment of a well to enhance production of
oil or gas, e.g., fracturing, acidizing, and so on.
[0073] Sweep circuit--an electronic or mechanical device which
creates a waveform with a regularly changing frequency or
amplitude, usually a linearly varying frequency and a constant
amplitude.
[0074] Treatment--the act of applying a process or substance to
something to give it particular properties.
[0075] Treatment fluid--a fluid designed and prepared to resolve a
specific wellbore or reservoir condition.
[0076] Well--a deep hole or shaft sunk into the earth, e.g., to
obtain water, oil, gas, or brine.
DETAILED DESCRIPTION
[0077] In the following description, numerous details are set forth
to provide an understanding of the present disclosure. However, it
may be understood by those skilled in the art that the methods of
the present disclosure may be practiced without these details and
that numerous variations or modifications from the described
embodiments may be possible. At the outset, it should be noted that
in the development of any such actual embodiment, numerous
implementation--specific decisions may be made to achieve the
developer's specific goals, such as compliance with system related
and business related constraints, which will vary from one
implementation to another. Moreover, it will be appreciated that
such a development effort might be complex and time consuming but
would nevertheless be a routine undertaking for those of ordinary
skill in the art having the benefit of this disclosure. In the
summary and this detailed description, each numerical value should
be read once as modified by the term "about" (unless already
expressly so modified), and then read again as not so modified
unless otherwise indicated in context. Also, in the summary and
this detailed description, it should be understood that a range
listed or described as being useful, suitable, or the like, is
intended to include support for any conceivable sub-range within
the range at least because every point within the range, including
the end points, is to be considered as having been stated. For
example, "a range of from 1 to 10" is to be read as indicating each
possible number along the continuum between about 1 and about 10.
Furthermore, one or more of the data points in the present examples
may be combined together, or may be combined with one of the data
points in the specification to create a range, and thus include
each possible value or number within this range. Thus, (1) even if
numerous specific data points within the range are explicitly
identified, (2) even if reference is made to a few specific data
points within the range, or (3) even when no data points within the
range are explicitly identified, it is to be understood (i) that
the inventors appreciate and understand that any conceivable data
point within the range is to be considered to have been specified,
and (ii) that the inventors possessed knowledge of the entire
range, each conceivable sub-range within the range, and each
conceivable point within the range. Furthermore, the subject matter
of this application illustratively disclosed herein suitably may be
practiced in the absence of any element(s) that are not
specifically disclosed herein.
[0078] In some embodiments, degradable diverter is used to plug a
fluid flow path, within the wellbore, e.g., a bridge plug, or
connected to the wellbore, e.g., a fracture, and degradation is
monitored using the reflection of tube waves, which are also
referred to herein as pressure waves or an interrogating signal.
The pressure waves can be generated either by a special pressure
signal emitter or by a fluid hammer, e.g., by suddenly stopping a
treatment fluid pump in such a way that a pressure wave results.
When a pressure wave reflects from an interface or change in the
tubular media, the reflection is related to the original wave, but
modified by the character of the reflector.
[0079] According to some embodiments herein, the pressure waves
reflected to the surface or other sensor location are from a
wellbore plug such as a ball, or an open fracture. The reflection
from a wellbore plug, normally having the same sign as the
interrogating signal, implies that the sealing ball did not
degrade. The change or disappearance of reflections from the
wellbore plug indicates degradation of the plug and lost sealing of
the zone and/or readiness for production or injection.
[0080] Conversely, in some embodiments, a sealed fracture in which
a diverter has been placed produces no reflection, or a small or
undetectable reflection, and appearance of a reflection from the
perforation interval with a negative sign compared to the
interrogating signal can indicate degradation of diversion material
and the establishment or restoration of a hydraulic connection
between the wellbore and a fracture, suggesting that the fracture
is readied for production or injection as the case may be.
[0081] Two extreme types of pressure wave reflection are thus of
particular interest in some embodiments: those of a closed end
wellbore, and those of an open end. A closed end is one in which
there is little or no compliance at the reflector; a capped pipe is
an example of this. An open end is one in which there is a large
compliance at the reflector; a pipe ending in a large tank is an
example of this. Such compliance can consist of a significant
sealed volume of fluid, a free surface, or a connection to a
reservoir, such as a hydrocarbon reservoir. The fluid flow
characteristics of the connection between the two affect the
magnitude of the reflection; a free flowing connection, i.e., an
open end, produces the largest reflection; a non-flowing
connection, i.e., a closed end, similarly produces a large
reflection; and a connection with significant flow resistance
produces a smaller reflection. At some point the impedance or
resistance of the connection approximates the characteristic
impedance of the pressure wave media, i.e., the wellbore, casing or
other material having a surface interfacing the fluid filling the
wellbore. At this point all of the incoming energy may be absorbed
by the resistance of the connection, leading to no reflection at
all, and this non-reflecting end is referred to as a
terminator.
[0082] With reference to the example shown in FIG. 1, PVC pipe used
as a simulated well bore was interrogated with a positive pressure
wave. A small hydraulic accumulator was attached to the pipe via a
ball valve at 101 m (331 ft) from the pressure source to imitate an
open fracture connected to the well. The far end of the tubing
located at 165 m (541 ft) was capped to imitate a sealed bridge
plug. When the ball valve was closed to imitate a fracture sealed
by a diverter for reflection traces 1 and 2, there was no simulated
perforation reflection 10 at 101 m, and a full end reflection 12.
In the case of traces 3 and 4, the ball valve was opened to
simulate an open fracture, giving a low resistance connection to a
compliant volume and yielding an open end type reflector. This
reflection 10 was visible as an inverted or down-going pulse. The
far end gives a positive reflection 12, which is proportionally
reduced by partial reflection 10. In this manner, the
interpretation of the pressure wave reflections is illustrated for
purposes of some embodiments disclosed herein.
[0083] With reference to the embodiments illustrated in FIG. 2, the
pressure wave 14 is generated in the well 16 by pressure signal
emitter or source 18 and/or by a sharp stop of the fracturing pump
20, and is propagated downhole. The reflections are received at
pressure sensor 22. The pressure wave reflection 24 is formed by
the partially degraded ball 26 seating on bridge plug 30. The
remaining signal wave portion 28 passing the plug 30 forms
reflection 32 at the intact ball 34 seated on the bridge plug 36.
The reflection 24 is weak if present at all, and may not be
detected.
[0084] The embodiments of FIG. 2 have potential application in a
multistage operation wherein degradable balls 26, 34 are used to
seal respective bridge plugs 30, 36 to isolate intervals in
respective stages. After the stimulation, the balls 26, 34 degrade
to permit production. Monitoring of the degradation of the balls
26, 34 in some embodiments, involves an analysis of the detected
reflections 24, 32 for their presence as well as amplitude. In the
case of degraded ball 26 the reflection 24 from bridge plug 30 is
weak and/or may be absent, whereas the reflection 32 from the next
bridge plug 36 is detected and is strong. If the ball 26 were not
degraded, the reflected wave 24 would have strong positive
amplitude compared to the interrogating pressure pulse 14, and
there would be no passing wave 28 and thus no reflected wave 32
would be detected.
[0085] In the embodiments illustrated in FIG. 3, wherein like
reference numerals indicate like parts and features, the pressure
wave 14 is generated in the well 16 by pressure signal emitter or
source 18 and/or by a sharp stop of the fracturing pump 20, and is
propagated downhole as in FIG. 2, and the reflections received at
pressure sensor 22. In this case, the pressure wave reflection 42
is formed by the open hydraulic fracture 44. Diversion material 46
seals the perforations 48 or other hydraulic passages in the
fracture 50, whereas the fracture 44 is hydraulically connected to
the well via perforations 52. These perforations are only partially
sealed with diversion material 54 that has been degraded. The
pressure wave 14 passes fracture 50 without reflections, and
reflects from fracture 44.
[0086] The embodiments of FIG. 3 have potential application in a
diversion operation in new fracturing treatments or in refracturing
treatments, wherein diversion material 46 is pumped to seal the
hydraulic connections between the fractures 44, 50 and the wellbore
38 before the next successive stimulation stage. Monitoring of the
degradation of the diverting material 46 is done by analysis of the
reflected waves coming from the depth of particular fracture. At
the end of a stimulation stage, before sealing, the fracture from
the stage will produce reflection with strong negative amplitude
compared to the interrogating signal. After sealing the fracture
with diversion material 46 the reflection from that interval will
become weak or disappear. When the diversion material degrades,
there will again be a strong reflection from that depth with
negative amplitude, indicating that the fracture is ready for
returning the well to service.
[0087] To monitor degradation of a ball or diverter material
occurring over an order of several minutes, in some embodiments,
multiple frequent pressure pulses can be generated from the
interrogating signal, e.g. every 1 second to 3 minutes, or every 10
to 30 seconds, and degradation can be determined from a change in
the reflected pulses, i.e., appearance and strengthening in the
case of perforation plugs, or weakening and disappearance in the
case of bridge plugs. Where a well is a hybrid of FIGS. 2 and 3,
i.e., may contain bridge plugs and perforation plugs, the
reflections at each plug type can be distinguished by the different
signs as noted above, e.g., positive sign reflections for the
bridge plugs and negative sign reflections for the open
fractures.
[0088] In some other embodiments, fast degradation events can be
monitored using a sweep signal having a period longer than the
event, which is generated by a special pulsing source, e.g., a
modified fracturing pump. Splitting the sweep signal into shorter
overlapping intervals and deconvolution of the reflections can show
any change in the reflector and therefore degradation.
[0089] In some embodiments, to monitor degradation occurring over
longer periods, e.g., from 0.5 to 24 hours, such as 1 to 4 hours,
in addition to or in place of a special pulsing source, the fluid
hammer generated every time the fracturing pump(s) are stopped can
be used, such as, for example, frac pump stopping before and after
placing the ball or diversion material, as well as after minibreak,
ISIP test, break in, end of stage, and so on.
[0090] In some embodiments, to measure of degradation over a period
of 1 or more days, if desired, a pulsing source and reflection
detector can be left in place on location connected to the well
after completion of the stimulation treatment. The pulsing source
can send multiple pulses or sweep signals over a day. Because of
the relatively long monitoring time, a high number of pulses or
long sweep pressure signals can be used, with stacking of the
reflections detected to improve signal to noise ratio so that a
relatively small, weak and/or inexpensive pressure signal emitter
can be used. Gradual changes in the reflected waves can reveal
kinetics of long-term degradation of a ball or diversion material.
The measurement tool, in some embodiments, can automatically send
data to a remote location for analysis.
[0091] Monitoring of the degradation of the degradable diverters in
some embodiments can be used to change one or more operating
parameters of the well, e.g., in response to the changes in the
observed reflections, proportional changes in the operation of the
well can be instituted, in some embodiments automatically, or a
decision to begin producing the well and/or the zones ready to be
placed into production (or injection) can be made based on actual
measured degradation, rather than an estimated time. This can be an
advantage when downhole conditions are not precisely known and/or
other factors make a precise determination of the degradation time
otherwise unpredictable, and according to some embodiments herein
the well can be placed into production earlier than the period
estimated for complete degradation if this is the case, or
production can be delayed until complete degradation is confirmed
if it is not the case. For example, the time required for the
degradation of diversion materials and/or wellbore plugs is
sensitive to fluid salinity, pressure, and temperature, as well as
the physical condition and quality of the diverter or plug itself,
which may degrade differently under (generally unknown) downhole
conditions, and the use of a laboratory master curve may not give a
precise prediction of the kinetics of the process.
[0092] With reference to FIG. 4, a process flow diagram illustrates
some of the steps, operations, events, tasks, or features for
treatment of a well according to the method 100, involving
monitoring of diverter degradation in accordance with some
embodiments of the disclosure. In operation 102, a diverter, which
may be a mechanical diverter or a chemical diversion material, is
placed in the wellbore, perforation, fracture or the like, e.g., a
bridge plug isolating a first portion of the wellbore from a second
portion of the wellbore, or diversion material placed in a
perforation, fracture, etc., and in step 104, fluid flow is
diverted past the diverter, e.g., in a later pumping operation of
the same stage and/or another stage(s) of the treatment. After
placement 102, e.g., during diversion 104 or other progression of
the treatment, or after completion of the stimulation treatment,
the diverter is exposed to degradation conditions in operation 106.
Degradation conditions can include pressure and temperature
conducive to degradation, contact with a solvent or chemical
reactant, which may be present or exist in the downhole environment
or may be introduced and/or activated in a distinct step.
[0093] To check the degradation status of the diverter element, a
pressure wave is generated in operation 108 and the response sensed
in step 110. In some embodiments, analysis of the data from the
pressure wave interrogation is performed in operation 112, and if
desired, the data and/or analysis may be reported, e.g., to a
remote location or control system. In some embodiments, the
degradation status is monitored in operation 114, and after
determining that the degradable diverter has substantially
degraded, in step 116, the well is placed in service, e.g.,
production or injection of fluids from or to the reservoir or
otherwise flowing fluid through the flow path of the (degraded)
diverter.
[0094] By performing an operation, the present disclosure may refer
to placing the well in service for example by flowing through the
previously plugged path; but it may also be forcing the degradation
of the diverter for example by pumping an acid or alkaline
compound, this can also be other operation such as opening a sleeve
or flowing back in order to improve the configuration of the well
for further hydrocarbon production.
[0095] With reference to FIG. 5, there is shown a method 200 for
treatment of a well involving checking diverter degradation after
interruption of a treatment schedule in accordance with some
embodiments of the disclosure. In the method 200, treatment of the
well is initiated in step 202 per a planned treatment schedule,
which may include schedules for proppant pumping or other treatment
fluid introduction into the well and for mechanical or chemical
diverter placement 204, and treatment progresses past at least one
diverter placement 204 until the planned treatment is interrupted
in event 206. Before resuming the treatment, the status of the
diverter(s) is checked by pressure wave generation 208 and response
sensing 210, e.g., to determine that the diverter is still intact
and/or has not degraded to the point that diverter functionality is
impaired. If needed or desired, the treatment schedule can be
adjusted in step 212, and in operation 214 the treatment is resumed
according to the original treatment schedule or the modified
treatment schedule. Following further treatment, in some
embodiments, the method may further proceed, in a manner similar to
actions 108 to 116 in FIG. 4, with pressure wave generation 216,
response sensing 218, analysis and/or reporting of the data 220,
degradation status monitoring 222, and fluid flow 224 through the
flow path(s), e.g., by placing the well in service.
[0096] With reference to FIG. 6, there is shown a flow diagram for
the method 300 for treatment of a well involving monitoring of
diverter placement and degradation in accordance with some
embodiments of the present disclosure. The method 300 proceeds with
diverter placement 302, followed by pressure wave generation 304,
and response sensing 306 to confirm proper diverter placement prior
to fluid flow diversion 308. Next, in operation 310 steps 302 to
308 can optionally be repeated as desired for one or more
subsequent stages. Following completion of the desired stage(s),
the diverter(s) is(are) subjected to degradation exposure 312, and
the method 300 may further proceed, in a manner similar to actions
108 to 116 in FIG. 4, with pressure wave generation 314, response
sensing 316, processing and/or reporting of the data 318,
degradation status monitoring 320, and fluid flow 322 through the
flow path(s), e.g., by placing the well in service.
EMBODIMENTS LISTING
[0097] In some aspects, the disclosure herein relates generally to
well re-stimulation methods and/or workflow processes according to
the following Embodiments, among others:
Embodiment 1
[0098] A method for treating a well, comprising: (a) placing a
degradable diverter in a flow path of the well to divert fluid flow
from the flow path; (b) exposing the degradable diverter to
degradation conditions; (c) sensing a response to a pressure wave
generated in the well to determine whether the degradable diverter
has substantially degraded; and (d) after determining that the
degradable diverter has substantially degraded, placing the well in
service and flowing fluid through the flow path.
Embodiment 2
[0099] the method of Embodiment 1, wherein the degradable diverter
comprises a mechanical diverter, such as a ball received in a
bridge plug seat.
Embodiment 3
[0100] the method of Embodiment 1 or Embodiment 2, wherein the
degradable diverter comprises a chemical diversion material.
Embodiment 4
[0101] the method of any one of Embodiments 1-3, wherein the flow
path comprises a perforation and/or fracture in communication with
the well.
Embodiment 5
[0102] the method of any one of Embodiments 1-4, wherein the flow
path comprises a first portion of the wellbore isolated from a
second portion of the wellbore by the diverter.
Embodiment 6
[0103] the method of any one of Embodiments 1-5, further comprising
continuously or periodically generating the pressure wave and
sensing the response to monitor the placement of the diverter,
degradation of the diverter, or a combination thereof.
Embodiment 7
[0104] the method of any one of Embodiments 1-6, wherein the
placement or degradation of the diverter or both are monitored by
changes in the sensed response.
Embodiment 8
[0105] the method of any one of Embodiments 1-7, wherein the
pressure wave is generated at a frequency from 1 per second to 1
per minute.
Embodiment 9
[0106] the method of any one of Embodiments 1-8, wherein the
pressure wave generation comprises a sweep circuit comprising a
regularly changing frequency.
Embodiment 10
[0107] the method of any one of Embodiments 1-9, wherein the
pressure wave has overlapping intervals.
Embodiment 11
[0108] the method of any one of Embodiments 1-10, further
comprising deconvoluting the sensed response, e.g., to improve
sensitivity and allow weak emitter signal such as signal to noise
ratio less than 10 dB.
Embodiment 12
[0109] the method of any one of Embodiments 1-11, further
comprising automatically sending data derived from the sensed
response to a remote receiver.
Embodiment 13
[0110] the method of any one of Embodiments 1-12, wherein the
pressure wave is generated by a fluid hammer.
Embodiment 14
[0111] the method of Embodiment 13, wherein the fluid hammer is
formed by suddenly stopping pumping of treatment fluid, e.g., into
the well.
Embodiment 15
[0112] the method of any one of Embodiments 13-14, wherein the
fluid hammer is formed at a time in the operation that is one or
more or all of the following: before diverter placement, after
diverter placement, after a minibreak, for an instantaneous shut-in
pressure (ISIP) test, for break in, at the end of a stage, or a
combination thereof.
Embodiment 16
[0113] the method of any one of Embodiments 1-15, wherein the
pressure wave is generated by a pressure signal emitter device in
communication with the well.
Embodiment 17
[0114] The method of any one of Embodiments 1-16, wherein the
flowing of the fluid in (d) comprises producing reservoir fluid, or
wherein the well comprises a production well.
Embodiment 18
[0115] The method of any one of Embodiments 1-17, wherein the
flowing of the fluid in (d) comprises fluid injection into a
subterranean formation, or wherein the well comprises an injection
well.
Embodiment 19
[0116] The method of any one of Embodiments 1-17, wherein
Embodiment 20
[0117] The method of any one of Embodiments 1-17, wherein
Embodiment 21
[0118] The method of any one of Embodiments 1-20, wherein
Embodiment 22
[0119] The method of any one of Embodiments 1-21, wherein
Embodiment 23
[0120] A method for treating a well, comprising: (a) initiating a
treatment sequence according to a planned treatment schedule
comprising introducing treatment fluid into the well in a plurality
of stages; (b) placing a degradable diverter in a flow path of the
well to divert treatment fluid from the flow path; (c) interrupting
the treatment schedule comprising shutting in the well; (d) sensing
a response to a pressure wave generated in the well to determine
whether the degradable diverter has degraded; and (e) after
determining that the degradable diverter has not degraded, resuming
the treatment sequence; wherein the method is optionally according
to none or any one of the methods of Embodiments 1-22.
Embodiment 24
[0121] The method of Embodiment 23, wherein the resumption of the
treatment sequence is according to the planned treatment
schedule.
Embodiment 25
[0122] The method of Embodiment 23 or Embodiment 24, wherein the
resumption of the treatment sequence is according to a new
treatment schedule revised in response to the interruption.
Embodiment 26
[0123] The method of any one of Embodiments 23-25, further
comprising exposing the diverter to degradation conditions.
Embodiment 27
[0124] The method of Embodiment 26, further comprising sensing a
response to a pressure wave generated in the well to determine
whether the degradable diverter has degraded.
Embodiment 28
[0125] The method of Embodiment 27 further comprising after
determining that the degradable diverter has degraded, flowing
fluid through the flow path.
Embodiment 29
[0126] A method for treating a well, comprising: (a) placing a
degradable diverter in a flow path of the well to divert treatment
fluid from the flow path; (b) sensing a response to a pressure wave
generated in the well to confirm the placement of the degradable
diverter; (c) diverting fluid flow from the flow path; (d)
repeating (a)-(c) one or more times for a plurality of respective
degradable diverters placed in respective flow paths; (e) exposing
the diverters to degradation conditions; (f) sensing a response to
a pressure wave generated in the well to determine whether the
degradable diverters have degraded; and after determining that the
degradable diverters have degraded, placing the well in service and
flowing fluid through the flow paths; wherein the method is
optionally according to none or any one of the methods of
Embodiments 1-28.
[0127] Although only a few exemplary embodiments have been
described in detail above, those skilled in the art will readily
appreciate that many modifications are possible in the example
embodiments without materially departing from this disclosure. For
example, any embodiments specifically described may be used in any
combination or permutation with any other specific embodiments
described herein. Accordingly, all such modifications are intended
to be included within the scope of this disclosure as defined in
the following claims. In the claims, means-plus-function clauses
are intended to cover the structures described herein as performing
the recited function and not only structural equivalents, but also
equivalent structures. Thus, although a nail and a screw may not be
structural equivalents in that a nail employs a cylindrical surface
to secure wooden parts together, whereas a screw employs a helical
surface, in the environment of fastening wooden parts, a nail and a
screw may be equivalent structures. It is the express intention of
the applicant not to invoke 35 U.S.C. .sctn.112(f) for any
limitations of any of the claims herein, except for those in which
the claim expressly uses the words `means for` or `step for`
together with an associated function without the recitation of
structure.
* * * * *